The present invention relates to a vehicle seat provided with a load detector.
A vehicle equipped with an air bag may be provided with load detectors to detect whether a passenger is sitting on a seat. The load detectors may also detect the weight of the passenger sitting on the seat to optimally adjust the amount of generated gas when the air bag is inflated.
Japanese Unexamined Patent Publication No. 11-1153 describes such load sensors. A seat is supported on left and right rails, each fixed to the floor of a vehicle by a mount bracket, so that the seat can be moved back and forth along the rails. A load sensor is arranged between each rail and the associated mount bracket. The weight of the seat is detected based on load signals generated by the load sensors.
A child restraint system (CRS) may be installed on a vehicle seat. When securing the CRS to the vehicle seat with a seat belt, the restraining force of the seat belt applies a large downward load on the seat. This affects the detection of each load sensor and results in the sensors detecting a weight that is greater than the actual weight of the CRS. As a result, the detection may, for example, erroneously indicate that a passenger is sitting on the seat. Hence, a vehicle seat that enables detection of a CRS is sought after.
It is an object of the present invention to provide a vehicle seat that detects a child restraint system.
To achieve the above object, the present invention provides a seat including a seat belt fastened to an anchor, which is located on one side of a rear portion of the seat.
The seat includes a first load sensor attached to the seat in the vicinity of the anchor to detect load and generate a first detection value representing the load detected by the first load sensor. A second load sensor is attached to the seat at a side opposite to the first load sensor to detect load and generate a second detection value representing the load detected by the second load sensor. A control unit is connected to the first and second load sensors. The control unit determines whether a child restraint apparatus is present based on the first and second detection values.
The present invention also provides a method for detecting whether a child restraint apparatus is fastened to a seat by a seat belt that is fastened to an anchor. The anchor is located on one side of a rear portion of the seat. The seat includes a first load sensor attached to the seat in the vicinity of the anchor to detect load and generate a first detection value representing the load detected by the first load sensor. A second load sensor is attached to the seat at a side opposite to the first load sensor to detect load and generate a second detection value representing the load detected by the second load sensor. The method includes comparing the first and second detection values, obtaining a difference between the first and second detection values, comparing the difference with a predetermined rear differential reference value, and determining that the child restraint apparatus is present when the second detection value is greater than the first detection value and the difference is greater than the rear differential reference value.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.